Foam dressing with integral porous film

ABSTRACT

Wound dressings and wound inserts including a porous film layer and at least a channel, forming wound inserts including a porous film layer and at least a channel, and wound-treatment wound inserts.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/015,385, filed Nov. 13, 2013, which is a divisional of U.S. patentapplication Ser. No. 13/316,997, filed Dec. 12, 2011, which claimspriority to U.S. Provisional Patent Application No. 61/423,405, filedDec. 15, 2010. Each of the above-referenced applications areincorporated herein by reference for all purposes.

BACKGROUND

1. Field of the Invention

The present invention relates generally to healing of wounds andwound-treatment therapies. More particularly, but not by way oflimitation, the present invention relates to fluid-instillation andnegative-pressure wound therapies.

2. Background Information

Clinical studies and practice have shown that providing a reducedpressure in proximity to a tissue site augments and accelerates thegrowth of new tissue at the tissue site. The applications of thisphenomenon are numerous, but application of reduced pressure has beenparticularly successful in treating wounds. This treatment (frequentlyreferred to in the medical community as “negative pressure woundtherapy,” “reduced pressure therapy,” or “vacuum therapy”) provides anumber of benefits, including faster healing and increased formulationof granulation tissue. Typically, reduced pressure is applied to tissuethrough a wound insert (e.g., a porous pad or other manifold device).The wound insert typically contains cells or pores that are capable ofdistributing reduced pressure to the tissue and channeling fluids thatare drawn from the tissue. The wound insert can be incorporated into awound dressing having other components that facilitate treatment, suchas, for example, a drape (e.g., adhesive surgical drape). Instillationfluids (e.g., irrigation fluids and/or medicaments) may be used inconjunction with negative pressure wound therapy to promote healingand/or improve efficacy. One example of a system for delivering activesolutions to a wound is disclosed in U.S. Pat. No. 6,398,767.

In certain applications, providing negative pressure to the wound siteis clinically advantageous, but formation of granulation tissue isundesirable. For example, providing negative pressure to orthopediccavity wounds containing hardware such as plates, rods, or pins may helpthese wounds heal faster. However, the formation of granulation tissuearound this hardware can be harmful.

SUMMARY

Wound inserts, and methods for making and using them, are presented.

Some embodiments of a method of manufacturing a wound insert compriseobtaining a member comprising open-celled reticulated foam, the memberfurther comprising a first surface, a second surface, and anuncompressed thickness; obtaining a platen press comprising a firstplaten and a second platen; heating the first platen to a firsttemperature; placing the member in the platen press such that the firstsurface faces the first platen and the second surface faces the secondplaten; and compressing the member to a compressed thickness for acompression time.

Additionally, some embodiments may further comprise the step of forminga porous film layer on the first surface of the member. Otherembodiments may further comprise the step of forming a porous film layeron the second surface of the member. Still other embodiments may furthercomprise removing a portion of the porous film layer from the firstsurface. The removing step may comprise laser cutting, laser etching,die cutting, or water cutting. Still other embodiments may furthercomprise forming channels in the porous film layer.

In certain embodiments, the compressed thickness is less than aboutone-tenth, one-ninth, one-eighth, one-seventh, one-sixth, or one-fifththe uncompressed thickness. In some embodiments, the uncompressedthickness is about 0.5 inch and the compressed thickness is about 0.05inch. In some embodiments, the first platen, the second platen, or bothmay be heated to a temperature between about 160° C. and about 180° C.;in specific embodiments, the platen may be heated to a temperature ofabout 175° C. The compression time may between about 15 minutes andabout 30 minutes.

In some embodiments, the member may comprise polyurethane, such aspolyurethane-polyester or polyurethane-polyether; polyolefins, such aspolypropylenes (PP) or polyethylenes (PE); silicone polymers;polyvinylchloride; polyamides; polyesters; acrylics; thermoplasticelastomers such as styrene-butene-styrene (SBS) orstyrene-ethylene-butene-styrene (SEBS); polyether-amide block copolymers(PEBAX); elastomers such as styrene butadiene rubber (SBR); ethylenepropylene rubber (EPR); ethylene propylene diene modified rubber (EPDM);natural rubber (NR); ethylene vinyl acetate (EVA); polyvinyl alcohol(PVOH); polyvinyl acetal; or polyvinyl butyral (PVB). Additionally, foammember may comprise a bioabsorbable polymer, examples of which includepolylactic acid, polylactide (PLA), polyglycolic acid, polyglycolide(PGA), and polycaprolactone (PCL).

Other embodiments of a method of manufacturing a wound insert comprisethe steps of: obtaining an open-celled reticulated foam member having afirst surface, a second surface, and a thickness between the first andsecond surfaces; felting the first surface of the member to form afelted layer; and forming at least one channel in the felted layer.

In certain embodiments, the at least one channel may be in fluidcommunication with the second layer through the thickness. The feltingstep may further comprise applying heat and pressure to the member. Insome embodiments, forming may comprise laser cutting, water cutting, ordie cutting.

The member may comprise polyurethane, such as polyurethane-polyester orpolyurethane-polyether; polyolefins, such as polypropylenes (PP) orpolyethylenes (PE); silicone polymers; polyvinylchloride; polyamides;polyesters; acrylics; thermoplastic elastomers such asstyrene-butene-styrene (SBS) or styrene-ethylene-butene-styrene (SEBS);polyether-amide block copolymers (PEBAX); elastomers such as styrenebutadiene rubber (SBR); ethylene propylene rubber (EPR); ethylenepropylene diene modified rubber (EPDM); natural rubber (NR); ethylenevinyl acetate (EVA); polyvinyl alcohol (PVOH); polyvinyl acetal; orpolyvinyl butyral (PVB). Additionally, foam member may comprise abioabsorbable polymer, examples of which include polylactic acid,polylactide (PLA), polyglycolic acid, polyglycolide (PGA), andpolycaprolactone (PCL).

Certain embodiments are directed to a wound insert. Some embodimentscomprise open-celled reticulated foam comprising a first surface, asecond surface and a thickness between the first and second surfaces,wherein the first surface of the open-celled reticulated foam comprisesa porous film layer and at least one channel.

Embodiments of a wound insert may comprise polyurethane-polyester orpolyurethane-polyether; polyolefins, such as polypropylenes (PP) orpolyethylenes (PE); silicone polymers; polyvinylchloride; polyamides;polyesters; acrylics; thermoplastic elastomers such asstyrene-butene-styrene (SBS) or styrene-ethylene-butene-styrene (SEBS);polyether-amide block copolymers (PEBAX); elastomers such as styrenebutadiene rubber (SBR); ethylene propylene rubber (EPR); ethylenepropylene diene modified rubber (EPDM); natural rubber (NR); ethylenevinyl acetate (EVA); polyvinyl alcohol (PVOH); polyvinyl acetal; orpolyvinyl butyral (PVB). Additionally, foam member may comprise abioabsorbable polymer, examples of which include polylactic acid,polylactide (PLA), polyglycolic acid, polyglycolide (PGA), andpolycaprolactone (PCL).

Other embodiments of a wound insert may comprise an open-celledreticulated foam member comprising a porous film layer, the porous filmlayer comprising a film thickness; and at least a channel in the porousfilm layer, wherein the at least one channel comprises a channel depth,the channel depth being equal to or greater than the film thickness;where the wound insert is configured to be disposed between a wound of apatient and a drape coupled to the skin adjacent to the wound.

Specific embodiments may further comprise at least a sealed edge joiningfirst and second surfaces. In various embodiments, the open-celledreticulated foam member may comprise polyurethane-polyester orpolyurethane-polyether; polyolefins, such as polypropylenes (PP) orpolyethylenes (PE); silicone polymers; polyvinylchloride; polyamides;polyesters; acrylics; thermoplastic elastomers such asstyrene-butene-styrene (SBS) or styrene-ethylene-butene-styrene (SEBS);polyether-amide block copolymers (PEBAX); elastomers such as styrenebutadiene rubber (SBR); ethylene propylene rubber (EPR); ethylenepropylene diene modified rubber (EPDM); natural rubber (NR); ethylenevinyl acetate (EVA); polyvinyl alcohol (PVOH); polyvinyl acetal; orpolyvinyl butyral (PVB). Additionally, foam member may comprise abioabsorbable polymer, examples of which include polylactic acid,polylactide (PLA), polyglycolic acid, polyglycolide (PGA), andpolycaprolactone (PCL).

Still other embodiments are directed to methods for removing fluids froma wound site. Certain embodiments of a method for removing a fluid froma wound site may comprise the steps of: obtaining a wound insertcomprising an open-celled reticulated foam member comprising a porousfilm layer, the porous film layer comprising a film thickness; and atleast a channel comprising a channel depth, the channel depth beingequal to or greater than the film thickness; obtaining a patient havinga wound; inserting the wound insert into the wound such that the porousfilm layer faces the wound; applying a drape such that the wound insertis disposed between the drape and the wound, and the drape is coupled toskin adjacent the wound; obtaining a vacuum source coupled to the woundinsert; and applying negative pressure to the wound insert.

Other embodiments may comprise the steps of obtaining a wound insertcomprising an open-celled reticulated foam member comprising a porousfilm layer, the porous film layer comprising a film thickness; and atleast a channel comprising a channel depth, the channel depth beingequal to or greater than the film thickness; obtaining a patient havinga wound; inserting the wound insert into the wound such that the porousfilm layer faces the wound; applying a drape such that the wound insertis disposed between the drape and the wound, and the drape is coupled toskin adjacent the wound; and actuating a fluid source coupled to thewound insert such that fluid is delivered to the wound insert

The following drawings illustrate by way of example and not limitation.For the sake of brevity and clarity, every feature of a given structureis not always labeled in every figure in which that structure appears.Identical reference numbers do not necessarily indicate an identicalstructure. Rather, the same reference number may be used to indicate asimilar feature or a feature with similar functionality, as maynon-identical reference numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate by way of example and not limitation.For the sake of brevity and clarity, every feature of a given structureis not always labeled in every figure in which that structure appears.Identical reference numbers do not necessarily indicate an identicalstructure. Rather, the same reference number may be used to indicate asimilar feature or a feature with similar functionality, as maynon-identical reference numbers.

FIG. 1 illustrates an embodiment of a method of making a wound insert.

FIG. 2A illustrates a perspective view of an embodiment of a foammember.

FIG. 2B illustrates a side view of embodiment of a foam member.

FIG. 3A illustrates a schematic view of an embodiment of an uncompressedfoam member in a press.

FIG. 3B illustrates a schematic view of an embodiment of a compressedfoam member in a press.

FIG. 4 illustrates a side view of an embodiment of a wound insert.

FIG. 5A illustrates a perspective view of an embodiment of a woundinsert comprising a plurality of channels.

FIG. 5B illustrates a perspective view of an embodiment of a woundinsert comprising a channel.

FIG. 6A illustrates a side view of a wound insert comprising a pluralityof channels.

FIG. 6B illustrates a side view of a wound insert comprising a pluralityof channels.

FIG. 7 illustrates a schematic diagram of a wound insert in a wound.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The term “coupled” is defined as connected, although not necessarilydirectly, and not necessarily mechanically; two items that are “coupled”may be integral with each other. The terms “a” and “an” are defined asone or more unless this disclosure explicitly requires otherwise. Theterms “substantially,” “approximately,” and “about” are defined aslargely but not necessarily wholly what is specified, as understood by aperson of ordinary skill in the art.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, awound-treatment method that “comprises,” “has,” “includes” or “contains”one or more steps possesses those one or more steps, but is not limitedto possessing only those one or more steps. Likewise, a wound dressingthat “comprises,” “has,” “includes” or “contains” one or more elementspossesses those one or more elements, but is not limited to possessingonly those elements. For example, in a wound dressing that comprises oneof the present wound inserts and a drape, the wound dressing includesthe specified elements but is not limited to having only those elements.For example, such a wound dressing could also include a connection padconfigured to be coupled to a negative pressure wound therapy (NPWT)apparatus (e.g., including a vacuum source and/or a fluid source).

Further, a device or structure that is configured in a certain way isconfigured in at least that way, but it can also be configured in otherways than those specifically described.

Referring now to FIGS. 1-3B, embodiments of a foam dressing 8 andmethods for manufacturing such a dressing are shown.

FIGS. 2A and 2B depict perspective and side views of an open-celledreticulated foam member 10, having a first surface 12, a second surface14, sides 11, and edges 13. Foam member 10 may be of any suitable shape,including a rectangular prism or a cylinder. In certain applications,foam member 10 may comprise a regular or irregular polygon having adepth, depending on the shape of the wound into which it is intended tobe inserted. One of skill in the art will appreciate that the dimensionsof foam member 10 in the accompanying figures have been exaggerated forclarity.

An open-celled reticulated foam has a netlike microstructure, with fewif any closed cells. In certain embodiments, the porosity can range from95%-98%, though less porous or more porous foams may be used. In certainembodiments, foam member 10 may comprise a polyurethane, such aspolyurethane-polyester or polyurethane-polyether; polyolefins, such aspolypropylenes (PP) or polyethylenes (PE); silicone polymers;polyvinylchloride; polyamides; polyesters; acrylics; thermoplasticelastomers such as styrene-butene-styrene (SBS) orstyrene-ethylene-butene-styrene (SEBS); polyether-amide block copolymers(PEBAX); elastomers such as styrene butadiene rubber (SBR); ethylenepropylene rubber (EPR); ethylene propylene diene modified rubber (EPDM);natural rubber (NR); ethylene vinyl acetate (EVA); polyvinyl alcohol(PVOH); polyvinyl acetal; or polyvinyl butyral (PVB). Additionally, foammember 10 may comprise a bioabsorbable polymer, examples of whichinclude polylactic acid, polylactide (PLA), polyglycolic acid,polyglycolide (PGA), and polycaprolactone (PCL). Methods ofmanufacturing open-celled reticulated foam are well known. Open-celledreticulated foam is commercially available from a variety of sources,including Kinetic Concepts, Inc., San Antonio, Tex.

In the embodiments shown in FIGS. 2A and 2B, first surface 12, secondsurface 14, and sides 11 of foam member 10 are unfinished. In otherwords, reticulated cells extend to all surfaces of the foam member. Incertain applications, these unfinished surfaces allow negative pressureto be applied to the wound site and encourage granulation tissue to growinto the foam member, which may be desirable depending on the nature ofthe wound. In other applications, however, the formation of granulationtissue in the foam member may complicate or impede the healing process,even though it would be desirable to provide negative pressure to thewound site. As discussed in more detail below, certain surfaces may beleft unfinished if it is desirable that granulation tissue grows intothem.

Referring now to FIGS. 3A and 3B, foam member 10 having an uncompressedthickness U is shown schematically between a first platen 22 and asecond platen 24 in a press (not shown). Suitable presses arecommercially available from numerous sources, including Carver Press,Wabash, Ind. First platen 22, second platen 24, or both may be capableof being heated to a specified temperature. In the embodiment shown,first platen 22 is heated to a specified temperature. In certainembodiments, the temperature may range between 160° C. and 180° C.,depending on the foam used. Foam member 10 is placed in the press suchthat first surface 12 faces first platen 22, and second surface 14 facessecond platen 24. The platens 22, 24 are brought together, compressingfoam member 10 to a compressed thickness C. Compressed thickness C offoam member 10 is a fraction of uncompressed thickness U. In certainembodiments, compressed thickness C may be less than one-tenth,one-ninth, one-eighth, one-seventh, one-sixth or one-fifth uncompressedthickness U.

Porous film layer 16 is formed by applying heat and pressure to the foammember; such application of heat and pressure is sometimes known as“felting.” Porous film layer 16 is sometimes known as a “felted layer.”In such a process, foam member 10 is held in a compressed positionbetween first platen 22 and second platen 24 for a specified period oftime. In certain embodiments, the period of time ranges between 15 and30 minutes, though the time period may be more or less depending on thematerial used for foam member 10. Generally, the lower the temperatureof the platen, the longer foam member 10 must be held in compression.Overheating the platen, or applying pressure for too long, may riskdamaging foam member 10 by charring or burning it.

After the specified time period has elapsed, foam member 10 may beremoved from the press. As shown in FIG. 4, the pressure and heat willform a porous film layer 16 on first surface 12 having thickness F.Porous film layer 16 is integral with foam member 10. In other words,porous film layer 16 and foam member 10 form a single unitary body.Porous film layer 16 will be comparatively smoother than any unfinishedor non-felted surface, such as second surface 14 in the embodimentshown. Further, the pores in porous film layer 16 are substantiallysmaller than the pores throughout foam member 10 in general or on anynon-felted side.

In certain embodiments, it may be desirable to form a porous film layeron second surface 14 of foam member 10. Those of skill in the art willunderstand that it is possible to form porous film layers on firstsurface 12 as well as on second surface 14. Methods of forming a porousfilm layer 16 include heating both platens before compressing foammember 10, or first compressing and heating one side then compressingand heating the other side. In such embodiments, the porous film layerformed on second surface 14 is integral with foam member 10. That is,the porous film later formed on second surface 14 and foam member 10comprise a single unitary body.

Perspective views and side views of various embodiments of wound insert8 are shown in FIGS. 5A-6B. First surface 12 of wound insert 8 comprisesporous film layer 16 that intersects with sides 11 at edges 13, as wellas one or more channels 18. Channels 18 may take a variety of shapes,including straight, curved, zig-zag, spiral, circular, or any fancifulshape. As shown in FIG. 5A, channels 18 may run to edge 13, or may beself-contained on first surface 12. The exact shape of channels 18 maybe configured for optimal fluid removal or fluid instillation at thewound site. As shown in FIGS. 6A and 6B, the depth of channels 18 may beabout equal to thickness F of film layer 16. In other embodiments, thedepth of channels 18 may be greater than thickness F of film layer 16.And in still other embodiments, the depth of channels 18 may be lessthan the thickness F of film layer 16.

In certain embodiments, channels 18 may be formed on first surface 12 byremoving portions of porous film layer 16. In some embodiments, portionsof porous film layer 16 may be removed with a laser cutter (not shown).In one example, the desired channel pattern is drawn in a CAD program.The channel pattern may be transmitted to a computer-controlled lasercutter, which then applies a laser beam to the porous film layer 16 ofthe wound insert 8. An advantage of using a laser cutter instead ofother methods to remove material is that the focal depth of the laser iseasily adjusted, and thus the depth of channels 18 may be preciselycontrolled. A laser may be more easily adjusted to remove material onlyfrom porous film layer 16, and not from foam member 10. Additionally, alaser with an adjustable focal depth may more easily create channels 18having different depths: for example, some channels 18 may have a depthequivalent to thickness F of porous film layer 16, while other channels18 may have a depth greater than F. Other material-removal processes maybe used, however. For example, a water jet cutter, a die press, oretching may be used to remove material from porous film layer.

Channels 18 may also be formed in other ways, such as by molding. A moldwith the desired channel pattern may be coupled to one or both platensduring the heating and compression steps. In certain embodiments, use ofa mold will prevent porous film from being formed in the channels 18. Inother embodiments, channels 18 may comprise a layer of porous film 16.

Referring again to FIGS. 6A and 6B, cross-sectional views of a woundinsert are shown. As shown in FIG. 6A, in some embodiments, sides 11 areunfinished, such that the open-celled reticulated foam member 10 isexposed. As shown in FIG. 6B, in other embodiments, sides 11 arefinished with a seal or seam 15. Sides 11 or second surface 14 may befinished or unfinished depending on the desired application. Leavingsides 11 or surface 14 unfinished may encourage granulation tissuegrowth into foam member 10. Sealing or seaming or otherwise finishingsides 11 or surface 14 will prevent such tissue growth. Granulationtissue growth is desirable in some instances but not in others.

Referring now to FIG. 7, wound insert 8 is shown as part of a woundtreatment system 30. In the embodiment shown, wound insert 8 is shownplaced in wound 50 of a patient (not shown) such that first surface 12comprising porous film layer 16 and channels 18 faces the wound surface52. In other embodiments, wound insert 8 may comprise more than oneporous film layer 16 disposed on, for example, second surface 14; theseadditional porous film layer(s) 16 may or may not include channels 18.

A drape 32 is placed over wound 50 and wound insert 8 such that woundinsert 8 is between drape 32 and wound 50. Drape 32 is coupled to theskin 54 of the patient. Wound insert 8 is coupled to a wound treatmentapparatus 42 by conduit 36. Apparatus 42 may comprise a vacuum sourceconfigured to apply negative pressure to wound insert 8 through conduit36. Apparatus 42 may further comprise a fluid source configured todeliver a fluid through conduit 36 to wound insert 8. For example,apparatus 42 may comprise a pump configured to pump a fluid throughconduit 36 to wound insert 8. Examples of such fluids include amedicinal fluids, antibacterial fluids, or irrigation fluids. Variouswound therapy systems and components are commercially available throughand/or from KCI USA, Inc. of San Antonio, Tex., U.S.A.

Conduit 36 can comprise a single lumen conduit (e.g., switched between avacuum source and/or a fluid source) or can comprise multiplesingle-lumen conduits or a multi-lumen conduit such that, for example,fluid can be delivered and/or negative pressure can be applied to woundinsert 8 individually or simultaneously. Or conduit 36 can comprisemultiple lumens (e.g., as in a single conduit with a central limit forapplication of negative pressure and/or fluid delivery and one or moreperipheral lumens disposed adjacent or around the central lumen suchthat the peripheral lumens can be coupled to a pressure sensor to senseand/or detect a pressure or negative pressure between drape 32 and woundsurface 52. In the embodiment shown, system 30 further comprises a wounddressing connection pad 34 configured to be coupled (and is showncoupled) to conduit 36. One example of a suitable connection pad 36 isthe “V.A.C. T.R.A.C.® Pad,” commercially available from KCI USA, Inc. ofSan Antonio, Tex., U.S.A. One example of a suitable drape 32 includesthe “V.A.C.® Drape” commercially available from KCI USA, Inc. (and itsaffiliates) of San Antonio, Tex., U.S.A.

Channels 18 provide a path of lower resistance between second surface 14through foam member 10 as compared to the path through porous film 16.Thus, when a fluid is instilled through wound insert 8, most or all ofthe fluid will tend to flow into wound 50 through channels 18. Andconversely, when fluids are being removed from wound 50, much or all ofthe fluid will flow up through channels 18, through foam member 10, andinto conduit 36.

The various illustrative embodiments of devices, systems, and methodsdescribed herein are not intended to be limited to the particular formsdisclosed. Rather, they include all modifications and alternativesfalling within the scope of the claims.

The claims are not intended to include, and should not be interpreted toinclude, means-plus- or step-plus-function limitations, unless such alimitation is explicitly recited in a given claim using the phrase(s)“means for” or “step for,” respectively.

We claim:
 1. A wound insert comprising: a foam member having a topsurface and a bottom surface, the foam member comprising open-celledfoam; a felted layer configured to allow passage of negative pressure,the felted layer forming at least a portion of the bottom surface; atleast one channel in the felted layer, wherein the at least one channelcomprises a channel depth, the channel depth being at least equal to athickness of the felted layer; and wherein the wound insert isconfigured to be disposed between a wound of a patient and a drapecoupled to skin adjacent to the wound.
 2. The wound insert of claim 1,wherein the thickness of the felted layer is less than about one-fifth athickness of the foam member.
 3. The wound insert of claim 1, whereinthe at least one channel has a circular shape.
 4. The wound insert ofclaim 1, wherein the foam member and the felted layer each comprisepores, and wherein the pores in the felted layer are substantiallysmaller than the pores in the foam member.
 5. The wound insert of claim1, wherein a thickness of the foam member is between the top surface andthe bottom surface of the foam member, and wherein the at least onechannel is in fluid communication between the top surface and the bottomsurface through the thickness of the foam member.
 6. The wound insert ofclaim 1, wherein the at least one channel is defined by material removedfrom the felted layer.
 7. A wound insert comprising: a felted porousfoam layer comprising a layer thickness; and at least one channel in thefelted porous foam layer, wherein the at least one channel comprises achannel depth, the channel depth being at least equal to the layerthickness; wherein the wound insert is configured to be disposed betweena wound of a patient and a drape coupled to skin adjacent to the wound.8. The wound insert of claim 7, wherein the felted porous foam layer isconfigured to allow the passage of negative pressure and to inhibittissue in-growth.
 9. The wound insert of claim 7, wherein the at leastchannel has a circular shape.
 10. The wound insert of claim 7, furthercomprising a foam member, wherein the felted porous foam layer forms atleast one surface of the foam member.
 11. The wound insert of claim 7,further comprising a foam member, wherein the foam member and the feltedporous foam layer each comprise pores, and wherein the pores in thefelted porous foam layer are substantially smaller than the pores in thefoam member.
 12. The wound insert of claim 7, further comprising a foammember having a first surface, a second surface, and a thickness betweenthe first surface and the second surface, wherein the at least onechannel is in fluid communication between the first surface and thesecond surface through the thickness of the foam member.
 13. The woundinsert of claim 7, wherein the at least one channel is defined bymaterial removed from the felted porous foam layer.
 14. The wound insertof claim 7, wherein the channel depth is greater than the layerthickness.